Endocrine effects of dopexamine vs. dopamine in high-risk surgical patients

Objectives: To compare the endocrine effects of dopexamine and dopamine on prolactin (PRL), dihydroepiandrosterone sulfate (DHEAS), cortisol, thyrotropin (TSH), and peripheral thyroid hormone serum concentrations in surgical patients at risk of developing postoperative complications because of hypoperfusion of various organ systems. Design and setting: A prospective, randomized, placebo-controlled, blinded clinical trial in an adult surgical intensive care unit in a university hospital. Patients: Thirty-two male surgical risk patients undergoing elective major abdominal surgery. Interventions: Patients were randomized to receive placebo (n = 8), dopexamine (0.5 mug kg(-1) min(-1), n = 8), dopexamine (1 mug kg(-1) min(-1), n = 8) or dopamine (5 mug kg(-1) min(-1), n = 8) on the first postoperative day. Measurements and results. All patients received either a placebo or catecholamine infusion for 24 h. Blood samples were obtained every 2 h for the next 2 days. PRL, DHEAS, cortisol, TSH, triiodothyronine, thyroxin, free triiodothyronine, and free thyroxin serum concentrations were determined by radioimmunoassay or luminescence immunoassay. Dopexamine (0.5 mug kg(-1) min(-1)) had no effects on serum concentrations of PRL or TSH. Higher doses of dopexamine (1 mug kg(-1) min(-1)) suppressed PRL secretion significantly, but not TSH. In contrast, infusion of dopamine (5 mug kg(-1) min(-1)) completely inhibited PRL and TSH secretion. DHEAS, cortisol, and thyroid hormone serum concentrations were not affected by either dopexamine or dopamine infusion. Measurements of hemodynamic parameters, peripheral oxygen saturation, diuresis, blood gases, and standard laboratory parameters were repeated hourly. Significant differences were not found between placebo, dopexamine (0.5 mug kg(-1) min(-1)) and dopamine (5 mug kg(-1) min(-1)) group. Dopexamine at 1 mug kg(-1) min(-1) increased the heart rate significantly. Conclusions: Routine postoperative optimizing of men undergoing abdominal surgical procedures with dopexamine at higher doses or dopamine induces at least partial hypopituitarism, which may possibly affect postoperative morbidity.